1. Field of the Invention
The present invention relates to a method for manufacturing high quality graphene by heating carbon-based self-assembly monolayers, and more particularly, relates to a method for manufacturing high quality large-area single-layered graphene by locally heating carbon source layers which can be convertible into graphene successively on a large area substrate.
2. Description of the Related Art
Graphene is a conductive material which is formed into a 2-dimensional honeycomb-shaped array of carbon atoms with a thickness of one atomic layer. When the combination structure of carbon atoms is piled up in 3-dimension, it becomes a graphite. When it is rolled up in one dimension, it transforms to a carbon nanotube. When it is formed into a ball shape, it becomes a fullerene. The 2-dimensional plane-structured graphene is interested to many researchers due to the 2-dimensional nano-scale phenomena and various applications.
In addition, the graphene is chemically and structurally very stable and it is a highly outstanding conductor transferring electrons 100 times faster than that of silicon and flowing electrical current 100 times more than that of copper. Its thermal conductivity is more than 2 times than that of diamond, its high mechanical strength is more than 200 times than that of steel, and it has transparency. Furthermore, it does not lose electrical conductivity even when stretching or folding because it has elasticity due to empty spaces in hexagonal honeycomb-shaped structures connected like a net. Recently, these unusual structures and physical properties of the graphene have been studied actively for replacement of ITO which is a primary material of transparent electrode and silicon which is a main material of semiconductor.
There are a number of manufacturing methods of the graphene such as pulling off it using a Scotch tape, an epitaxial growth method, separating the layers by oxidation of graphite and a chemical vapor deposition method. Above the rest, the best and well-known method is pulling off the graphene layer from graphite using the Scotch tape. This manufacturing method is simple and able to preserve unique characteristics of graphene, however, it also has disadvantages of difficulty in application to display or electronic device because it has a difficulty in large-area synthesis and it may not be clearly separated into graphene layer.
Meanwhile, the chemical vapor deposition can be used for manufacturing graphene by large area scale. Since the method heats an entire catalyst layer, carbon nuclei are created randomly on the surface of the catalyst layer and graphene can be grown around the center of the carbon nucleus. When a graphene grain grown around the center of the carbon nucleus butts another graphene grain, a grain boundary is formed. If each graphene grain does not match each other, defects are formed in grain boundary, and degrade electrical transport properties of the graphene. Defects within the graphene are known to accelerate reaction to surrounding environment. Moreover, a specific resistance of the grain boundary become greater from two times to ten times than that of a crystal graphene due to the grain boundary acting as a defect and thus, the chemical vapor deposition method may have a disadvantage in fabrication.
Korean registered patent No. 10-1174670 discloses a patterned fabrication method of graphene and Korean published patent No. 10-2012-0012271 discloses a manufacturing method of graphene which forms graphene by providing reaction gases including carbon sources and heating for the reaction of the gases. A transfer method for graphene on a substrate, contamination can occur from the solution for etching metal catalyst.
Therefore, a method for manufacturing the large area graphene without transferring process is required in order to maximize the advantages of the graphene by growing a large size of the graphene grain.